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Re: RFC 2141 on URN Syntax
>From w3c-dist-auth-request@w3.org Fri May 9 09:27:02 1997
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>Date: Fri, 09 May 1997 10:08:42 -0600
>To: Sukanta Ganguly <SGANGULY@novell.com>
>From: "Ron Daniel, Jr." <rdaniel@lanl.gov>
>Subject: Re: RFC 2141 on URN Syntax
>Cc: w3c-dist-auth@w3.org, urn-ietf@bunyip.com
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>At 08:54 AM 5/9/97 -0600, Sukanta Ganguly wrote:
>>Hi,
>> I wanted to mention some things about the rfc 2141 that I found
confusing.
>
>You should bring these questions up on the URN-WG list, not the
>Web DAV list. The URN list is urn-ietf@bunyip.com. I have added it
>to the CC list on this reply.
>
>>The syntax for a URN is specified as
>><URN> ::= "urn:" <NID> ":" <NSS>
>>and NSS also has ":" as a characters recognized within the <others>
rule.
>>Based on this
>> URN:foo:: -> Is this a valid URN ??
>
>That will depend on the rules for the namespace foo. The URN syntax
>is an attempt to be as liberal as possible so as to allow many
>different namespaces to exist. The rules for particular namespaces
>are intended to be much stricter. As an example, take a look at
>the URN-WG's internet draft on using bibliographic identifiers as URNs.
>Two of the namespaces in that document (ISBN and ISSN) disallow the use
>of ':' and many other characters. The third (SICI) has much more
>liberal rules because SICIs use lots of funny characters.
>
>>I feel that is ":" is used as a reserved terminator of a subsection of
a
>>rule then it should not be used in the recognized character sets for
the
>>other sub-sections of the rule. So I would imagine that ":" is not
present
>>as a recognizable character within the <other> rule of NSS subsection.
>
>The URN sytnax RFC takes a strong position on the first two occurances
>of ':'. After that, it is up to particular namespaces how ':' is or is
not
>used.
>
>>It just adds an extra amount of parsing effort for the applications to
have
>>this feature in their parsing mechanisms. I don't say that it is
impossible
>>to have it, but as a application developer, it would be a much messy
>>approach for me to write code that has this feature in it. I hope this
not
>>taken as a negative criticism.
>
>No, it is not taken as a negative criticism. However, one of the
requirements
>on URNs was the ability to grandfather legacy naming systems (such as
SICIs).
>If allowing ':' makes it easier to accomodate some naming schemes, then
we
>thought it would be worth some additional implementation difficulty.
The
>additional difficulty seems very small. The first two ':' characters
are
>required, so once one has stripped off the "urn:" prefix and the NID
>field with its colon, no more special treatment of ':' is required for
>a general URN parser. You will probably want to use the NID to lookup
>special parsing rules for the namespace, but that is another story.
>
>
>>I have a similar concern regarding the usage of "%" character within
the
>><NSS> subsection. This is what the rule resolution says
>><NSS> ::= 1*<URN chars>
>><URN chars> ::= <trans> | "%" <hex> <hex>
>><trans> ::= <upper> | <lower> | <number> | <other> | <reserved>
>><reserved> ::= '%" | "/" | "?" | "#"
>>
>>Here we observe that
>>
>> <NSS> ::= % could be a valid rule according to the rule
definition. At
>>the same time the system has another defination that says wheneever
"%" is
>>used two <hex> characters should be used.
>>
>> <NSS> ::=%%12 -> could also be a valid syntax for NSS.
>>
>>My suggestion here is to remove "%" from the <reserved> subsection of
<NSS>
>>rules.
>>
>>Please let me know if my thinking is along the lines of what the group
has
>>in mind or am I way out of wack.
>
>Single occurances of '%' are disallowed. '%' is supposed to ALWAYS mean
>that the next two characters will be hex digits that are taken to
>form an octet.
>
>
>>I appreciate your acceptance of my
>>participation in the group.
>>
>>Thank You
>>Sukanta Ganguly
>>
>>>>> Jim Whitehead <ejw@ics.uci.edu> 05/06/97 12:07PM >>>
>>
>>Of potential interest to participants of this WG.
>>
>>- Jim
>>
>>>To: IETF-Announce: ;
>>>Subject: RFC 2141 on URN Syntax
>>>Cc: rfc-ed@isi.edu
>>>Mime-Version: 1.0
>>>Date: Mon, 05 May 97 13:53:28 PDT
>>>Sender:ietf-announce-request@ietf.org
>>>From: RFC Editor <rfc-ed@isi.edu>
>>>
>>>
>>>A new Request for Comments is now available in online RFC libraries.
>>>
>>>
>>> RFC 2141:
>>>
>>> Title: URN Syntax
>>> Author: R. Moats
>>> Date: May 1997
>>> Mailbox: jayhawk@ds.internic.net
>>> Pages: 8
>>> Characters: 14077
>>> Updates/Obsoletes: None
>>>
>>> URL: ftp://ds.internic.net/rfc/rfc2141.txt
>>>
>>>
>>>Uniform Resource Names (URNs) are intended to serve as persistent,
>>>location-independent, resource identifiers. This document sets
>>>forward the canonical syntax for URNs. A discussion of both existing
>>>legacy and new namespaces and requirements for URN presentation and
>>>transmission are presented. Finally, there is a discussion of URN
>>>equivalence and how to determine it. This document is the product of
>>>the Uniform Resource Names Working Group of the IETF.
>>>
>>>This is now a Proposed Standard Protocol.
>>>
>>>This document specifies an Internet standards track protocol for the
>>>Internet community, and requests discussion and suggestions for
>>>improvements. Please refer to the current edition of the "Internet
>>>Official Protocol Standards" (STD 1) for the standardization state
and
>>>status of this protocol. Distribution of this memo is unlimited.
>>>
>>>This announcement is sent to the IETF list and the RFC-DIST list.
>>>Requests to be added to or deleted from the IETF distribution list
>>>should be sent to IETF-REQUEST@CNRI.RESTON.VA.US. Requests to be
>>>added to or deleted from the RFC-DIST distribution list should
>>>be sent to RFC-DIST-REQUEST@ISI.EDU.
>>>
>>>Details on obtaining RFCs via FTP or EMAIL may be obtained by sending
>>>an EMAIL message to rfc-info@ISI.EDU with the message body
>>>help: ways_to_get_rfcs. For example:
>>>
>>> To: rfc-info@ISI.EDU
>>> Subject: getting rfcs
>>>
>>> help: ways_to_get_rfcs
>>>
>>>Requests for special distribution should be addressed to either the
>>>author of the RFC in question, or to admin@DS.INTERNIC.NET. Unless
>>>specifically noted otherwise on the RFC itself, all RFCs are for
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>>>
>>>Submissions for Requests for Comments should be sent to
>>>RFC-EDITOR@ISI.EDU. Please consult RFC 1543, Instructions to RFC
>>>Authors, for further information.
>>>
>>>
>>>Joyce K. Reynolds and Mary Kennedy
>>>USC/Information Sciences Institute
>>>
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>Ron Daniel Jr. voice:+1 505 665 0597
>Advanced Computing Lab fax:+1 505 665 4939
>MS B287 email:rdaniel@lanl.gov
>Los Alamos National Lab http://www.acl.lanl.gov/~rdaniel
>Los Alamos, NM, USA, 87545
>
>
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